Kim Jong Un's half brother was assassinated with nerve poison one year ago — here's how it went down and the remaining unsolved mysteries

Kim Jong Un's elder half-brother was assassinated at a Malaysian airport on February 13, 2017.

One year later, many questions surrounding Kim Jong Nam's death remain unanswered.

It's been one year since the half-brother of North Korean leader Kim Jong Un was assassinated at a Malaysian airport — but the much of the case remains a mystery.

Kim Jong Nam was killed after two women rubbed a lethal nerve agent called VX on his face at Kuala Lumpur International Airport on February 13, 2017.

Both women, who have been charged with murder, have consistently maintained their innocence, claiming that they thought they were participating in a prank for a TV show. Four men have been charged as well, but are still on the run.

This is Kim Jong Nam. He was the eldest son of North Korean supreme leader Kim Jong Il and one of his mistresses, and was once considered a potential successor.

Here's video footage of the assassination, shown in video footage obtained by the Japanese TV channel Fuji Television, and annotated by the UK's Channel 5 News.

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The women accused of killing Kim Jong Nam have said they thought they were taking part in a prank for a TV show.

Doan Thi Huong, left, and Siti Aisyah.
Thomson Reuters

The suspected assassins — 25-year-old Indonesian Siti Aisyah and 29-year-old Vietnamese Doan Thi Huong — have both pleaded not guilty and said they thought they were taking part in a prank for a hidden-camera reality TV show.

Andreano Erwin, the ambassador, told GQ: "The first time we visited her, she kept asking when she could leave the jail. The second, she complained that she still hadn't been paid for the last prank. The third time, she accused us of being part of the prank.

"The fourth time, we showed her a newspaper proving Kim Jong-nam had died. When she saw it, she started to cry."

Aisyah's "trainers" led her through luxury hotels, malls, and airports in Malaysia and Cambodia, where she practised smearing non-lethal oil and hot sauce on Chinese-looking men, GQ reported.

She was paid between 400 and 650 Malaysian ringgit (£73/$101 to £119/$165) after her first few trial runs, the court heard in February.

Aisyah said she noticed that the substance she was given to smear Kim with smelled like machine oil, unlike the other liquids used in her other practice sessions.

Her handlers — a man who purported to be a Japanese national named James, and another claiming to be a Chinese man called Chang — were also later revealed to be North Koreans named Ri Ji U and Hong Song Hac, according to GQ.

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Kim Jong Nam was reportedly carrying vials of VX antidote in his bag when he was attacked.

News of the assassination reached South Korea before North Korea — because Malaysian officials mixed up the two Koreas and notified the wrong embassy.

After inspecting Kim's passport, Malaysian authorities accidentally confused the Democratic People's Republic of Korea — the formal name of North Korea — with the Republic of Korea, Reuters reported last year.

Within 24 hours of Kim's death, South Korean intelligence officials briefed lawmakers on the case, which was subsequently leaked to the country's media.

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North Korea held 11 Malaysians hostage after Kuala Lumpur opened an investigation into the case.

Police cars block the entrance of a sealed-off North Korea embassy in Kuala Lumpur in March 2017.
Lai Seng Sin/Reuters

North Korea engaged in a diplomatic spat with Malaysia as the government started investigating the murder.

North Korean state media KCNA accused Malaysia of politicising the murder after the country performed an autopsy on Kim Jong Nam's body.

"The Malaysian side is going to politicize the transfer of the body in utter disregard of international law and morality, and thus attain a sinister purpose," KCNA said at the time, according to NBC News.

Shortly afterward, two of them were let go. It's not clear what happened to the other nine.

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North Korea may have tried to kill Kim Jong Nam before — agents reportedly botched a separate assassination attempt in 2010.

In this photo taken Friday, June 4, 2010, Kim Jong Nam, the eldest son of North Korean leader Kim Jong Il, waves after his first-ever interview with South Korean media in Macau.
AP Photo/JoongAng Sunday via JoongAng Ilbo, Shin In-seop

An unnamed 50-year-old North Korean spy who defected to South Korea admitted to being part of a botched plot to run over Kim Jong Nam in China in 2010.

The assassination attempt — which involved hiring a taxi driver to carry out a hit-and-run — ultimately failed because the elder Kim was out of the country, Agence France-Presse reported in 2012.

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The animosity dates back to an unsanctioned trip to Disneyland Tokyo.

The Cinderella Castle at Disneyland Tokyo.
Wikimedia Commons

As Kim Jong Il's eldest son, Kim Jong Nam was once seen as his father's natural successor, instead of his younger half-brother Kim Jong Un.

However, Kim Jong Nam fell out of favour with his father in the early 2000s.

According to the Washington Post, the spat came when Kim Jong Nam and his family were caught trying to enter Japan to visit Tokyo Disneyland on false Dominican Republic passports.

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North Korean operatives have reportedly been trying to kill Kim Jong Nam's son, who has referred to Kim Jong Un as a "dictator" and is currently in hiding.

Video grab of a man who identified himself as Kim Han Sol, the son of Kim Jong Nam.
Cheollima Civil Defense/YouTube

Kim Han Sol has also previously referred to his uncle as a "dictator" and in 2012 told Finnish TV: "I've always dreamed that one day I would go back and make things better and make it easier for the people there."